VariableBoundTitledBorder.java

package variableEditorComponents;

import java.util.Observable;
import java.util.Observer;

import javax.swing.JComponent;
import javax.swing.border.TitledBorder;

import variableEditorUI.VariableEditorUIUpdateThread;
import variables.Variable;

/**
 * A TitledBorder which is bound to a Variable. When the Variable is changed,
 * the content of the title of the border is updated with the new contents of
 * the Variable.
 * 
 * @author Curran Kelleher
 * 
 */
public class VariableBoundTitledBorder extends TitledBorder implements
		Observer, VariableEditorComponent {
	private static final long serialVersionUID = -2182294459528860891L;

	/**
	 * The Variable to which this VariableBoundTitledBorder is bound.
	 */
	Variable variable;

	/**
	 * The component which uses this border. The displayability of this
	 * component is checked with every update from the update thread, and if it
	 * is not displayable, this border is removed as an Observer from the update
	 * thread, hopefully allowing it to be garbage collected.
	 */
	JComponent parent = null;

	/**
	 * The Value that is currently being displayed. This is checked against the
	 * actual value of the Variable periodically to decide whether or not to
	 * update the text with the current value of the Variable. This String is
	 * parseable into the actual value. It is generated by the method
	 * Value.toParseableString()
	 */
	String displayedValue = "";

	/**
	 * whether or not to display the value of the variable along with it's name
	 * in the title of the border.
	 */
	private boolean displayVariableValueInTitle = true;

	/**
	 * Construct a VariableBoundTitledBorder which is bound to the specified
	 * Variable.
	 * 
	 * @param variable
	 *            the variable to edit
	 * @param parent
	 *            The component which uses this border. The displayability of
	 *            this component is checked with every update from the update
	 *            thread, and if it is not displayable, this border is removed
	 *            as an Observer from the update thread, hopefully allowing it
	 *            to be garbage collected. If this is null, no updates will
	 *            occur.
	 */
	public VariableBoundTitledBorder(Variable variable, JComponent parent) {
		super("");
		this.variable = variable;
		this.parent = parent;
		VariableEditorUIUpdateThread.getInstance().addObserver(this);
		updateWithCurrentVariableValue();
	}

	/**
	 * Construct a VariableBoundTitledBorder which is bound to the specified
	 * Variable.
	 * 
	 * @param variable
	 *            the variable to edit
	 * @param parent
	 *            The component which uses this border. The displayability of
	 *            this component is checked with every update from the update
	 *            thread, and if it is not displayable, this border is removed
	 *            as an Observer from the update thread, hopefully allowing it
	 *            to be garbage collected. If this is null, no updates will
	 *            occur.
	 * @param displayVariableValueInTitle
	 *            whether or not to display the value of the variable along with
	 *            it's name in the title of the border.
	 */
	public VariableBoundTitledBorder(Variable variable, JComponent parent,
			boolean displayVariableValueInTitle) {
		this(variable, parent);
		this.displayVariableValueInTitle = displayVariableValueInTitle;
		updateWithCurrentVariableValue();
	}

	/**
	 * Updates the content of the title to reflect the current value of the
	 * variable.
	 * 
	 */
	public void updateWithCurrentVariableValue() {
		String valueString = variable.evaluate().toParseableString();
		setTitle(variable.toString().replace('_', ' ')
				+ (displayVariableValueInTitle ? (" : " + valueString) : ""));
		displayedValue = valueString;
		if (parent != null)
			parent.repaint();
	}

	/**
	 * Get the update from the VariableEditorUIUpdateThread
	 */
	public void update(Observable o, Object arg) {
		if (o == VariableEditorUIUpdateThread.getInstance())
			// if this component is no longer usable, remove it as an Observer.
			if (parent != null) {
				if (!parent.isDisplayable())
					VariableEditorUIUpdateThread.getInstance().deleteObserver(
							this);
				else if (!variable.evaluate().toParseableString().equals(
						displayedValue))
					updateWithCurrentVariableValue();
			} else
				// if (parent == null)
				VariableEditorUIUpdateThread.getInstance().deleteObserver(this);
	}

	/**
	 * This method does nothing, since the border never changes the value of the
	 * variable, it only displays it.
	 */
	public void bindToVariableEditorComponent(
			VariableEditorComponent componentToUpdate) {
	}

	/**
	 * 
	 * Sets whether or not to display the value of the variable along with it's
	 * name in the title of the border.
	 */
	public void setDisplayValue(boolean displayVariableValueInTitle) {
		this.displayVariableValueInTitle = displayVariableValueInTitle;
	}
}